Front / rearend weights for coilovers

Topsterguy · March 20, 2013, 05:30:27 PM

Hey Folks! I'm going to use QA-1 coilovers in the front and back of the 37 flatback I'm building , and I need to know the weight of the front and back of the car to get the spring rate to use. ie if the car's about 3000 pounds (?)would it be about 1600 front and 1400 back.?? Anyone know what a 37 would be?? Thanks! Larry

parklane · March 20, 2013, 09:30:10 PM

if you google that, it says 24-2600 depending on model.

Topsterguy · March 20, 2013, 09:41:41 PM

Quote from: "parklane"if you google that, it says 24-2600 depending on model.

Sorry, I shoulda added that I'm using a SBC / T-5 , and the front end is all stock Mustang , and it's a tudor flatback.

kb426 · March 20, 2013, 09:57:13 PM

My 32 pickup weighs more than 3200. That is with a steel sbf, tremec 3550, 9" rear with mark vi disc brakes, 16 gallon fuel tank, lots of wiring. etc. This was weighed on the grain elevator's scales. Surprised me. I was careful about what I used when building this.

Topsterguy · March 20, 2013, 10:41:58 PM

Quote from: "kb426"My 32 pickup weighs more than 3200. That is with a steel sbf, tremec 3550, 9" rear with mark vi disc brakes, 16 gallon fuel tank, lots of wiring. etc. This was weighed on the grain elevator's scales. Surprised me. I was careful about what I used when building this.

After looking around I found that a stock 37 sedan weighs 2696 pounds, so I would say mine would be about 3000 or so. Now I just need which spring rate to use for the coilovers. QA lists 375,500, 600, and 700. Another guy suggested he read about a guy with a 37 cabriolet used 375's front and 200's in the back coil overs.

chimp koose · March 21, 2013, 12:11:30 AM

There is a chart on speedway motors for coilover shock mounting that gives the weight of average street rods front and rear by model and year based on sbc/auto driveline.It also gives conversion rates for angled /vs vertical mounted shocks for the spring rate.An idea might be to make tubes the intended installed height of the coilovers for your car at the desired ride height and then find a stock car guy or chassis shop that would rent/lend you a set of portable scales to weigh your car at all 4 corners. Once you know the corner weights you should be able to select the right spring.

Harry · March 21, 2013, 12:44:43 PM

I have a '37 Ford tudor, Chev powered up in Cobble Hill. Bring your scales and we can weigh it.
jarvis210@shaw.ca

chimp koose · March 21, 2013, 01:30:59 PM

http://static.speedwaymotors.com/images/charts/255-3235B.jpg A chart with recommended spring rates based on axle weights.

wayne petty · March 21, 2013, 02:13:57 PM

i have been thinking about this for a while...

on straight axles.. the coilover springs support the weight directly...

but on control arm front suspension... there should be an additional calculation...

as the control arm becomes a lever..

if the shock mount is at 50% of the length and i think its closer to 65 to 75% out .. the spring rate is different if you want the suspension to actually absorb impacts and not ride like a brick...

i personally don't have a clue of how to calculate this..

but i would imagine that the ride height needs to be established.. so you know the aprox compression height of the spring..

with the percentage of length from the inner pivot and the overall length from the inner pivot to probably the center of pivot for the lower ball joint.. you should be able to select a spring that is right in area... without being too stiff or to soft..

somebody should be able to create a graph... or a calculator for it.. in fact... there are several.. but they are straight spring rate calculators...

http://www.pontiacracing.net/js_coil_spring_rate.htm

wait... forget what i said..

this site below has exactly what i was talking about...

http://www.ridetech.com/info/spring-rate-calculator/

darn... i hate to come up with something that is obvious knowledge and somebody else has already figured it out..

sorry to take you on a buggy ride...

Beck · March 21, 2013, 09:05:15 PM

I think the spring rate is dependent on how the car is set up. If you really want it in the weeds you need heavier springs. This will sacrafice the ride. You need the heavier springs to avoid tire rub and/or bottoming out. If you are willing to raise the car a bit then you can let the springs work like they are supposed to and soften the ride.
The only way to get one on the ground at the shows and get it up for a nice ride is with air ride, which I have never had. I have always sacraficed ride for the "cool factor".

Topsterguy · March 27, 2013, 01:27:34 AM

Thanks again, guys....some good info here !